Wrinkle-resistant cotton fabrics with improved moisture absorption



United States Patent 3 441,366 WRINKLE-RESISTANT COTTON FABRICS WITH IMPROVED MOISTURE ABSORPTION Andrew G. Pierce, Jr., and John G. Frick, Jr., New

Orleans, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Aug. 23, 1965, Ser. No. 481,985 Int. Cl. D06m 11/08 US. Cl. 8116.3 6 Claims ABSTRACT OF THE DISCLOSURE Moisture regain properties of aminoplast-treated, wrinkle-resistant cellulosic textile fabrics are improved by adding an inert inorganic salt to the treatmg formulation.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, Wlth the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

The treatment of cotton fabrics to give them wrinkle resistance and wash-wear, or smooth drying, properties is a common operation. These treatments usually consist of the application to the fabric of finishing agents that can react with themselves (polymerize within the cellulose) or crosslink with the cellulose and fix the structure of the cellulose fiber. The fabric is stabilized thereby in a smooth form, to which it will return after a deformation such as creasing or wrinkling. For these treatments, the most common agents now in use are the methylol amide compounds formed by the reaction of formaldehyde with polyfunctional organic amides. Some examples are d methylol ethyleneurea, dimethylol ethyltriazone, trimethylol melamine, and the methylol ureas. In some instances, formaldehyde may be used alone as the agent for imparting wrinkle resistance.

There are some disadvantages in these treatments, however. One disadvantage is that the moisture absorptivity of the cotton is reduced by the treatment. The relatively high moisture absorption normally present in cotton is often desirable. In cotton garments, it allows greater takeup and dissipation of body moisture, and contributes thereby to the comfort of the wearer, particularly in humid weather. This has been a marked advantage that cotton fabrics possessed in comparison with fabrics made from fibers with an inherently poor moisture absorption. The usual wrinkle resistance treatments, by reducing moisture absorptivity, give a fabric that will make a less comfortable garment than untreated cotton fabric would make.

It is known that the loss of moisture absorptivity in these treatments can be prevented by conducting the treatment in a manner that allows the cotton to stay swollen throughout, for instance, by conducting the treatment while the cotton remains wet with water. Treatments conducted in this manner, however, usually do not give the fabric much ability to resist wrinkling in the dry state, the condition in which it is normally used. In the few 1nstances such treatments have given wrinkle resistance, the required procedure has proven troublesome and expensive.

In our application, Ser. No. 290,264, filed June 24, 1963, a process is described, and claimed, for producing cotton fabrics with a high degree of wrinkle-resistance and washwear properties, with little or no reduction in moisture absorptivity. This is accomplished by using ordinary methylol amide finishing agents in the usual procedure but including a nonvolatile, water-soluble organic compound in the treating solution. The additive organic com- 'ice pound must be inert or have only low reactivity toward the methylol amide finishing agent and its catalyst, otherwise the stabilizing action of the agent will be inhibited or entirely eliminated. Examples of such nonvolatile, water-soluble organic compounds are dimethyl ether of tetraethylene glycol; monoethyl ether of triethylene glycol; water-soluble polyethylene glycol; and the like.

It has now been found that certain inorganic salts may be added to solutions of methylol amide and formaldehyde finishing agents to improve the moisture absorption of wash-wear fabrics without adversely affecting the wrinkle-resistance of the treated cellulosic material. It is a critical requirement of these inorganic salts that they have good solubility in water, are nonvolatile, and are inert to the finishing agents and their catalysts. The use of inorganic salts instead of the organic compounds provides a distinct economic advantage. It is an advantage of these inorganic salts that in some instances they also impart superior properties to the treated cotton fabrics; that is, produce higher moisture absorption with the same degree of wrinkle-resistance.

In a typical treatment by the process of this invention, the solution applied to the cotton fabric would comprise about 5 to 10 weight percent of the methylol amide, 0.3 to 3.0 weight percent of a catalyst to promote the reaction of the methylol amide, S to 25 weight percent of the inorganic salt, and the remainder water. The above percentages are all based upon the weight of the solution. In some instances, the usual catalyst may be omitted and the inorganic salt may act as both additive and catalyst.

It is also within the scope of our invention to add minor proportions of other agents, such as those required to modify the feel or hand of the treated fabric.

As noted above, it is a critical feature of the process of our invention that the inorganic salt will not interfere with the catalyst-promoted reaction of the finishing agents. Known catalysts presently used in the art are usually acidic and, therefore, the salt must be acidic, or neutral. The use of a basic salt will deactivate the catalyst and must be avoided. In some instances the salt employed may have the same anion as the anion present in the catalyst. For example, when the catalyst employed is magnesium chloride, typical salts which may be used are sodium chloride, potassium chloride, lithium chloride, aluminum chloride, and the like. When the catalyst is zinc nitrate, typical inorganic salts useful in the process of our invention are sodium nitrate, potassium nitrate, lithium nitrate, and the like. Other chloride or nitrate salts may be used but it is desirable to use those that are most economical for commercial production. The amount of additive salt is adjusted to be sufficient to maintain enough swelling of the cellulose fiber to give improved moisture absorption but not great enough to prevent the development of Wrinkle resistance in the treated fabric when in the dry state. As noted above, amounts ranging from about 5 to 25 Weight percent salt on the weight of the solution is a good practice. The solution described is applied to the cotton fabric by presently-employed, commercial methods using commercially-available equipment.

In the process of this invention, the cotton fabric is impregnated by passing the fabric into and through the treating solution and then removing the excess by squeezing between pad rolls until the amount of solution retained is about .50 to of the dry fabric weight. The fabric is dried, and then heated briefly at an elevated temperature, 1 to 3 minutes at to C., to cause reaction of the methylol amide or formaldehyde agent. In most instances it is preferable to wash the fabric after this treatment.

After such a treatment it is found that the cotton fabric has had a degree of wrinkle-resistance imparted to it that is as high as, or only slightly less than, that obtained without the use of the additive described in this invention. The moisture absorption of the fabric, however, is substantially higher than that of a fabric treated without the use of the additive. In fact, the moisture absorption of fabric treated by the process of this invention often approaches and sometimes exceeds that of the untreated fabric.

In the following examples the process and results of this invention are described in greater detail. The fabric used was a desized, scoured and bleached 80 x 80 cotton printcloth weighing 3.1 oz./sq. yd. The nitrogen-containing agents were commercially-available products and the formaldehyde was a commercial grade formalin containingabout 36.2% formaldehyde and 12% methanol as stabilizer.

Example 1 Five solutions containing dimethylol ethylene urea, catalyst, and an inert inorganic salt and three control solutions without salt were prepared. The solutions were applied to samples of the scoured cotton printcloth, dried at 60 C. for 7 minutes, heated at 160 C. for 3 minutes, washed and dried. The fabrics were tested for moisture regain and wrinkle recovery angle using methods described by the American Society for Testing Materials, (A.S.T.M. D1295-60T). Wrinkle recovery angle is used as a measure of wrinkle resistance. The same wrinkle recovery test was given to the fabrics while they were wet with water as a measure of their smooth drying properties. Composition of the solutions and results of the testing are shown in the following table.

the treated fabric without substantial lowering of the wrinkle recovery angle.

Example 3 A series of solutions was prepared containing 10% dimethylol ethyleneurea and different catalysts with, and without, additive salts. Results obtained from treating cotton fabrics with these solutions are shown in the following table:

Solution composition Fabric properties Wrinkle recovery It will be observed that the omission of salt caused the moisture absorption to be decreased whereas the inclusion of a salt additive caused the treated fabrics to retain about the same moisture absorption as the untreated fabric.

Example 4 Two solutions containing 10% dimethylol methyl carbamate and 0.5% zinc nitrate hexahydrate were prepared. One solution also contained 10% sodium nitrate as the Composition of solution Results of fabric testing Agent Catalyst Inert salt additive Wrinkle recovery (degrees, W+F) Moisture regain, Dry Wet percent The above data show that the use of an inert-salt additive causes an increase in the moisture regain of the treated fabric. This is accompanied in most instances by a small decrease in the dry, or standard, wrinkle recovery angle and a small increase in wet wrinkle recovery angle. The data also show that the moisture absorption of a fabric treated with a nitrogen containing agent is reduced from about 21-36% compared with the untreated control.

Example 2 A series of solutions containing 10%dimethylol ethyltriazone and various types and amounts of catalyst and inert salt, along with two controls without salt, were prepared and applied to cotton fabrics by the application procedures used in Example 1. Composition of the solutions and results of testing the treated fabrics are given in the following table:

Again, it will be observed that the presence of the salt additive caused an increase in the moisture absorption of inert salt additive. Fabric properties obtained by applying these solutions to cotton printcloth are as follows:

Wrinkle recovery (degrees, W+F) Moisture regain,

Solution applied Dry Wet percent Without additive salt 263 244 5.1 With 10% N aNO 242 256 6. 4 Untreated fabric. 178 6. 6

Here it will be observed that the presence of the additive salt caused an increase in moisture absorption of about 23 when compared with the fabric that was treated with a similar treating agent in which the salt was omitted.

Example 5 A solution was prepared containing 10% dimethylol ethyleneurea and 10% magnesium sulfate. In this instance, the high concentration of magnesium sulfate is serving as both additive and catalyst.

Wrinkle recovery (degrees, W+F) Moisture regain,

Dry Wet percent Treated fabric 256 229 6. 5 Untreated Control 181 167 6. 5

In this example, it will be observed that the wrinkle recovery is excellent when compared with the control and that the moisture absorption of the treated fabric has not been adversely affected by the treatment. Further, one salt has served as the catalyst for the nitrogen-containing agent and as the salt-additive.

Example 6 Two solutions were prepared containing formaldehyde and 0.5% zinc nitrate hexahydrate. Solution A contained no additive while solution B contained 10% sodium nitrate. Results of testing the treated fabrics are given below.

Wrinkle recovery (degrees, W+F) Moisture regain,

Dry Wet percent Solution A (no additive) 260 251 6. 2 Solution B (10% NaNOg) 250 266 7. 3 Untreated control 181 167 6. 5

Example 7 Two solutions were prepared, each containing 8% dimethylol ethyleneurea as the crosslinking agent and 10% monobasic sodium phosphate, (NaH PO as the inert salt additive. Fabric properties obtained by applying these solutions to cotton printcloth using two different catalysts are as follows:

Wrinkle recovery (degrees, W+F) Moisture Catalyst Dry Wet percent 0.5% ZI1 NO3 2-6H2O 251 223 6. 4 2% MgOlz-GHzO 260 241 6.3 Untreated control 181 167 6. 5

It will be observed from the above examples, that regardless of the particular finishing agent used, the inclusion of a selected inert, inorganic salt caused an increase in the moisture absorption of the treated fabric when compared with a treated fabric in which no salt was added to the treating solution. Dry wrinkle recovery was reduced to a small extent but remained much greater than that of the untreated fabric.

We claim:

1'. In a process for treating cellulosic fibrous materials with at least one crosslinking agent selected from the group consisting of formaldehyde, and the reaction products of formaldehyde with amides and a catalyst for said crosslinking agent, the improvement which consists of incorporating into the crosslinking formulation a quantity of from about 5 to 25 weight percent of an inert, inorganic, watersoluble, metallic salt selected from the group consisting of sodium chloride, magnesium sulfate, lithium chloride, sodium dihydrogen phosphate, and calcium chloride.

2. The process according to claim 1 wherein the inorganic metallic salt is sodium chloride.

3. The process according to claim 1 wherein the inorganic, metallic salt is sodium dihydrogen phosphate.

4. The process according to claim 1 wherein the inorganic salt is magnesium sulfate.

5. The process according to claim 1 wherein the inorganic, metallic salt is lithium chloride.

6. The process according to claim 1 wherein the inorganic, metallic salt is calcium chloride.

References Cited UNITED STATES PATENTS 3,082,122 3/1963 Krasny 8-1163 XR 3,094,705 6/1963 Reid et al. 8116.36 XR 3,181,927 5/1965 Roth et a1. 8-1163 3,372,979 3/1968 Reinhardt 8120 MAYER WEINBLATT, Primary Examiner.

US. Cl. X.R. 

